Clutch kits with 350 Nm torque capacity?

[weber]

Sorry elitee, I see that I can get the shipping options and rates by going all the way through to checkout and entering my address, but stopping short of confirming. Then I looked up PayPal's current payment conversion rate and I see the 949 Sports with rigid ceramic (or sprung organic) with shipping to Brisbane comes to AU$408 with the lowest cost shipping (USPS Flat Rate Box) and AU$492 with the most expensive (FedEx 8 days).

It's worth something to me to get it a bit sooner and to have local warranty support, so I'll see what Direct Clutch Services can do.

Based on what it says here (click the "Heavy Duty Button Kits" tab, halfway down the page, on the right) http://www.exedy.com.au/sports-tuff
I would expect the Exedy MZK-6944HDB to have similar torque capacity to the +50% clamp ceramics we are discussing here. MX5Mania have it listed at $530.

But the strange thing is, although I didn't actually get a figure for the HDB, Exedy told me the following torques for the HD and HDCB:
MZK-6944HD 210 Nm (organic)
MZK-6944HDCB 238 Nm (cushioned button)
These seem very low compared to other brands' comparable products and it makes me wonder if those aren't really ft-lb figures by mistake.

[weber]

Direct Clutch Services didn't reply at all to my $530 bid (they earlier quoted $575) while MX5plus (AutomotivePlus) at least told me they unfortunately couldn't do it, and MX5mania's Exedy doesn't come with a rigid centre, so I ended up ordering the NA6 clutch kit from 949Racing (with ceramic pucks and rigid centre). Thanks guys, for pointing me to that one.

[weber]

949Racing ceramic clutch installed in the electric MX-5. Not tested yet. Photos here:
http://forums.aeva.asn.au/weber-and-coulombs-mx5_topic980_post46879.html#46879

[nd55]

Davekmoore wrote:

> A Tesla makes do with one gear.

My understanding is that the rotating mass of an electric motor prohibits shifting in the normal sense.

However, this is truly bleeding edge stuff, so keep us posted.

Nick.

[weber]

Davekmoore wrote:

> A Tesla makes do with one gear.

My understanding is that the rotating mass of an electric motor prohibits shifting in the normal sense.

However, this is truly bleeding edge stuff, so keep us posted.

Nick.

Hi Nick. From Wikipedia "Tesla Motors' first two transmission suppliers were unable to produce transmissions, in quantity, that could withstand the gear-shift requirements of the high torque, high rpm electric motor."

Although the Tesla's motor peaks with about 200 kW at 6000 rpm, it goes out to 14,000 rpm and is still producing something like 100 kW out there. I think changing gears with 100 kW at 14,000 rpm may have been the problem for the original 2-speed transmission. This isn't as bad as a Formula 1, but then a Formula 1 gearbox only has to last 5 races (1525 km or 10 hours).

The new 4-puck ceramic clutch from 929 Racing is working just fine in our electric MX-5 and we haven't broken the gearbox or diff with our 360 Nm yet. Our rotating mass (or more correctly moment-of-inertia) is less than that of the original internal combustion engine and our flywheel is lighter. Making gear changes happen nicely is a matter of tuning the software that maps from the accelerator pedal position and actual rpm of the motor to the torque and rpm requests that are sent to the motor controller. We have this functioning much like the internal combustion engine, with similar "engine braking". Only in our case that motor braking puts charge back into the battery.

[weber]

I spoke too soon. It seems the NA6 clutch kit from 949Racing in the US (with ceramic pucks), despite claiming to withstand 350 Nm, cannot withstand more than about 240 Nm without slipping. I notice it's not on their website any more.

I plan to get the diaphragm spring doubled in the pressure plate, and see how it goes. It's embarrassing that I'll be asking Direct Clutch Services (Brisbane) to do the job when I should have just bought their slightly more expensive clutch kit in the first place.

For the latest on our electric MX-5 see
http://forums.aeva.asn.au/forums/weber-and-coulombs-mx5_topic980_post53165.html#53165